1. Field of the Invention
The present invention relates to a scroll compressor.
This application is based on Japanese Patent Application No. 2006-076621, the content of which is incorporated herein by reference.
2. Description of Related Art
In a scroll compressor, a spiral wall body of a fixed scroll and a spiral wall body of an orbiting scroll are disposed together, and revolving motion of the orbiting scroll with respect to the fixed scroll gradually decreases the volumes of compression spaces formed between the wall bodies, so that a fluid present in the compression spaces is compressed.
Various types of rotation-preventing mechanisms which allow the orbiting scroll to revolve while the rotation thereof is prevented have been known (for example, see Japanese Unexamined Patent Application Publication No. 11-13657).
Furthermore, in the scroll compressor as described above, since the compression capacity can be improved by increasing the compression ratio without increasing the size of the compressor, a compressor in which scroll members have shoulder shapes has been practically used (for example, see Japanese Unexamined Patent Application Publication No. 2002-5053).
In the scroll compressor, as a mechanism for preventing the rotation of the orbiting scroll, a pin-ring type rotation-preventing mechanism has been well known. For the pin-ring type rotation-preventing mechanism, a step of driving a pin and a ring in a casing of the scroll compressor must be performed, and since this step requires high machining accuracy, the manufacturing cost is disadvantageously increased. On the other hand, when the machining accuracy required in this step is degraded in order to avoid an increase in manufacturing cost, the rotation-preventing performance for the orbiting scroll is disadvantageously degraded.
In the pin-ring type rotation-preventing mechanism, as the number of pin-ring pairs is increased, a load per pin is decreased. However, when the number of pin-ring pairs is increased, there has been a problem in that the manufacturing cost of the scroll compressor is increased. On the other hand, when the number of pin-ring pairs is decreased in order to avoid the increase in manufacturing cost of the scroll compressor, the load per pin is disadvantageously increased.